將平面集合轉換為一對多C#/Linq

我有一個位于此類集合中的資料集：

public class AOClientData
{
    public int boclient_id { get; set; }
    public string beneficialownertype_name { get; set; }
    public int account_id { get; set; }
    public string fi_name { get; set; }
    public string acct_number { get; set; }
}
                           

看起來像這樣：

boclient_id    beneficialownertype_name   account_id     fi_name      acct_number
1001           Joe                        501            ABC          12345
1001           Joe                        502            BCA          54321
1002           Fred                       990            DDd          22334

目標是將其放入此類的集合中：

   public class ClientInfo 
    {
        public int boclient_id { get; set; }
        public string beneficialownertype_name { get; set; }
        public List<AccountInfo> Accounts { get; set; }
    }
               

與這個類是一對多的關系：

public class AccountInfo 
{
    public int account_id { get; set; }
    public string fi_name { get; set; }
    public string acct_number { get; set; }
}
       

結果應該是 ClientInfo 物件的集合，如下所示：

1001     Joe    {501,           ABC,  12345         },
                {502,           BCA,  54321         }
1002     Fred   {990,         DDd,  22334      }
            
            

這是我的嘗試，它確實加載了所有客戶端資料，但 ClientInfo.Accounts 屬性中的 AccountInfo 物件的屬性都是空的：

        List<ClientInfo> clientInfo = aoClientData
            .GroupBy(c => new { c.boclient_id, c.beneficialownertype_name })
            .Select(xGrp => new ClientInfo
            {
                boclient_id = xGrp.Key.boclient_id,
                beneficialownertype_name = xGrp.Key.beneficialownertype_name,
                Accounts = xGrp
                    .Select(c => new AccountInfo
                    {
                        account_id = c.account_id,
                        fi_name = c.fi_name,
                        acct_number = c.acct_number
                    })
                    .ToList()
            })
            .ToList();
                            

LINQ 有什么問題？

uj5u.com熱心網友回復：

您已將c變數重新aoCLientData用作您的專案和分組專案。在您的內部選擇中使用.Select(a => new AccountInfo...然后使用a代替c來選擇a.account_id,a.fi_name和a.acct_number。

var result = data
    .GroupBy(x => new { x.boclient_id, x.beneficialownertype_name })
    .Select(x => 
        new ClientInfo
        {
            boclient_id = x.Key.boclient_id,
            beneficialownertype_name = x.Key.beneficialownertype_name,
            Accounts = x.Select(a =>
                new AccountInfo 
                {
                    account_id = a.account_id,
                    fi_name = a.fi_name,
                    acct_number = a.acct_number
                }).ToList()
        });

uj5u.com熱心網友回復：

如果我查看您的代碼，我不明白為什么您會得到多個ClientInfos，每個都有一個nullproperty 值Accounts。我什至不希望有一個空的帳戶串列。

您是否嘗試過使用具有引數 resultSelector的 GroupBy的多載？

List<ClientInfo> clientInfo = aoClientData
    .GroupBy(

    // parameter keySelector:
    clientInfo => new
    {
        BoClientId = clientInfo.boclient_id,
        BeneficialOwnerTypeName = clientInfo.beneficialownertype_name,
    })

    // parameter resultSelector: for every key item with all its zero or more AOClientData
    // make one new ClientInfo
    (key, aoClientsWithThisKey) => new ClientInfo
    {
        boclient_id = key.BoClientId,
        beneficialownertype_name = key.BeneficialOwnerTypeName,
        Accounts = aoClientsWithThisKey.Select(aoClient => new AccountInfo
        {
            account_id = aoClient.account_id,
            fi_name = aoClient.fi_name,
            acct_number = aoClient.acct_number
        })
        .ToList(),
    })
    .ToList();

uj5u.com熱心網友回復：

這是解決方案：

var items = aoClientData.GroupBy(c => new { c.boclient_id, c.beneficialownertype_name })
    .Select(grp => new ClientInfo()
    {
        boclient_id = grp.Key.boclient_id,
        beneficialownertype_name = grp.Key.beneficialownertype_name,                            
    Accounts = grp.Select(r => new AccountInfo() 
    { 
        account_id = r.account_id,
        acct_number = r.acct_number
    }).ToList()
}).ToList();

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